Instinct and Discernment 



Lastly, in the case of all these dwellings, 

 the Mason-bee is man's free tenant; her in- 

 dustry makes use of the products of our own 

 industry. Can she have no other establish- 

 ments? She has, beyond a doubt; she pos- 

 sesses some constructed on the ancient plan. 

 On a stone the size of a man's fist, protected 

 by the shelter of a hedge, sometimes even on 

 a pebble in the open air, I see her building 

 now groups of cells as large as a walnut, now 

 domes emulating in size, shape and solidity 

 those of her rival, the Mason-bee of the 

 Walls. 



The stone support is the most frequent, 

 though not the only one. I have found nests, 

 but sparsely inhabited it is true, on the trunks 

 of trees, in the seams of the rough bark of 

 oaks. Among those whose support was a liv- 

 ing plant, I will mention two that stand out 

 above all the others. The first was built in 

 the lobe of a torch-thistle as thick as my leg; 

 the second rested on a stalk of the opuntia, 

 the Indian fig. Had the fierce armour of 

 these two stout cactuses attracted the atten- 

 tion of the insect, which looked upon their 

 tufts of spikes as furnishing a system of de- 

 fence for its nest? Perhaps so. In any case, 



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